Knit lace patterns often move segments of loops to the left or right -- this results in a decorative hole at one end of the moved loops and a stack of stitches at the other end. The order that the stitches appear in this stack influences the appearance of the finished lace. In hand-knitting terminology, this stacking order determines the lean of the decrease -- so one might have a left-leaning or right-leaning decrease.| Carnegie Mellon Textiles Lab